Wrap adjust device for controlling engagement between a web and roller

ABSTRACT

The temperature of a heat sensitive web is controlled by varying the contact area between the web and a thermo roller having an appropriate thermo energy device coupled to it. A wrap adjust roller is supported for movement along a circular path concentric with the periphery of the thermo roller and varies the surface area contact between web and thermo roller at different locations relative to the thermo roller.

Kingsley etal, 1

United; States Patent 11 1 31 "3, 5,72 1451 July/23,1974

' 221 Filed;

121] App]. No.:318,322

[5 1 WRAP ADJUST DEVICE Fon CONTROLLING ENGAGEMENT BETWEEN A WEB ANDROLLER [75] Inventors: William Kingsley; Robert F. Allis,

both of Rochester, N .Y.

I [73] Assignee: Xerox Corporatiomstamford,

Conn. Dec. 26, 1972 Related US. Application Data [62] Division ofSer. No. 171,819, Aug. 16, 1971.

52 US. Cl 219/469, 28/62,2l9/2,16,

, 1 y 219/471 51 1m.c|. "1105b 1/02 58 Field OfSearc h. ..219/2l6, 469, 470, 471,

[ I References Cited 7 UNITED STATES PATENTS 2,394,540 2/1946 Finzel "28/713 3/1965 lvzmto 28/713 3,356,831 12/1967 I Andrus et a1. 219/469 X 3,621,201 11/1971 Crane et 31. ..L 219/469 X 3,637,976 1/1972 Primary Examiner-J. D. Miller Assistant Examiner-Fred E. Bell Attorney, Agent, or Firm--James J. Ralabate; David C.

V 1 Petre; John B. Mitchell [57 I ABSTRACT The temperature of a heat sensitive web is controlled by varying the contact area between the web and a therrno rollerhaving an appropriate thermo energy device coupled to it, A wrap adjust roller is supported for movement along a circular path concentric with 1 the periphery of the thermo roller and varies the sun .face area contact between web and thermo roller at different locations relative to the thermo roller.

18 Claims, 4 Drawing Figures Ohta et a1, 219/469 X PATENIEU JUL 2 3 I974 shim or 2 "Fwm ADJU TDEVII v IENGAGEMENTQBETWEENA w n: AND ROLLER energy with the above referencedmigration imaging surface areaover which thermo-energy is exchanged CROSS-REFERENCE TO RELATED v APPLICATIONS- I This application is a divisional application of copending application; Ser. No. 171,819, filed Aug. 16, 1971.

and more specifically to methods and apparatus for exchanging thermo-energy with a web to control its temperature. The temperature control is used to process'a heat sensitive image recording member in web form.

A migration imaging system is disclosed in U.S. Pat. No. 3,520,681 and ,copending application Ser. No. 553,837, filed May 31, l966'now abandoned,'634 75.7, filed Apr. 25, I967; and.837,59l, filed June 30, 1969 now U.S. Pat. No. 3,580,962 and the disclosures of the foregoing are incorporated herein by reference. Broadlypthe above migration imaging system employs. an imaging member including image particles and a' softenable material. Electric forces associated with certain of the image particles cause the particles to migrate through the softenable material when its mechan- :icalresistance to the migration is reduced. The mechanical resistance of the softenable material is reduced by methods-including softening, heating, exposing to solvent vapors or liquids and combinations of the foregoing. The resent invention is concerned with heating and 000 ing the foregoing imaging. members and other heat sensitive members in web form.

A migration imaging member in web form maybe heated as part of a development step for forming'a visipa'ssing'the web over 'a thermo roller coupled to .a

thermo-energy device. A first heat exchange occurs ble image. The samefilm is also cooled to lock particles atspecified locations within the film. With other heat sensitive materials, heating and cooling may serve some other purpose. The problem in each case ishow'to control the exchange of energy with a webwithout raising or lowering the temperature of the web to a level at which thev member isfstructurally and/or functionally damaged. a v 2 Accordingly, it is an object of this invention to overcome the above-noted problems and limitations. Specifically, it is an object .of the present invention to devise methods and apparatusfor exchanging thermomember inweb form. I

Another object of the instant invention is to protect a heat sensitive web from being heated or cooled to temperatures that are structurally or functionally'unsuitable. 1 I i Yet another object of the invention is to effect rapid engagement and disengagement of a thermo-energy element with a web-member.

Still another object of this invention is to control the with a web.

Even ajfurther object of the instant invention is to contact a web with a thermo-energy device while the web is moving and to break the contact when the web a is stationary. I

These andother objects of the present invention are realized with novel web handling-methods and apparatus. Thermo-energy is exchanged with a web member while the web is in contact with the thermo roller and a second heat exchange is made when the web is separated from the roller. The engagement and separation of the web and thenno roller is accomplished with a wrap adjust device. The wrap adjust device includes a wrap roller joumaled in pivot arms that are rotatably supported about the rotation axis of the thermo roller.

The wrap roller moves around the periphery of the thermo roller along a coincident circular path. The position of the wrap roller relative-to the thermo roller determines whether the web is in contact with the thermo roller and the amount of surface area contact between them.

DESCRIPTION OF THE DRAWINGS vFIGS. 2-4 are schematic side elevation views of a web passed over wrap and thermo rollers with the wrap roller at a-different position in each figure illustrating different areas of. contact between the thermo roller and web including no contact.

a v DESCRIPTION a The migration imaging system of FIG. 1 employs a .therm'o roller 1- and wrap adjust device 2 for controlling the temperature of web 3. Web 3 is a migration imaging structure including a conductivesubstrate and a migration layer composedv of image particles and softenable material. The web is threaded through the machine between the supply 4 and take-up reel 5. Images are forrn'ed with the web as it is wound between the two reels by steps including: depositing electrostatic charge on the free or outer surface of the web as it travels past corotron 9; exposing the charged web to electromagnetic radiation (for example, a flying light spot) as it travels past exposure means 10; and developing the chargedand exposed web as it moves past the thermo roller by reducing the mechanical resistance of the web softenable material to migration by the image particles.

The reduction in mechanical resistance may be ef-' fected'by several methods including the presently concerned method of heating the softenable material.

The charging and exposing steps give rise to a latent electrical image which is rendered visible by development at the thermo roller. Solvent vapor and/or liquids may be used in addition to the heat. The heating reduces the mechanical resistance of the web by softeningit. The image particles associated with the latent electrical image migrate in depth through the developed softenable material therebycreating positive and negative images from the migratedand non-migrated particles. Process parameters such as charge levels, po-

lar'ities' and/or materials are controllable such that the exposed or the non-exposed particles are the image particles that migrate. For details in regard to the migr'ation image process, the reader is directed to the initially referenced Patent and Patent Applications. These references also include disclosures relating to washing away the softenable material and to splitting a soften- I able material to separate migrated and non-migrated particles. I

Thermoplastic deformation imaging processes and structures such as disclosed in U.S. Pat. Nos. 3,055,006; 3,196,011; and 3,113,179 are examples of 'the surface of a thermoplastic material with electric fields associated with charge deposited on the surface of the'thermoplastic. Heating and/or exposing to a solvent enables the thermoplastic to deform under the influence of the charge. 'When the thermoplastic is placed on a photoconductor, the process steps can include charging, exposing and developing as with the migration imaging process. The difference betweenthe processes include those involved in the developing step. In one developing step, particles migrate and in the other a surface deforms.

Heating and/or cooling web members is desirable in systems other than the foregoing. For example, a silver halide motion picture film requirescooling to protect the resin material of the film from heat generated by lamps'us'ed to protect the film images. In addition, the manufacture of web members may include a step wherein heatis applied to or subtracted from a web for diverse purposes. The present'invention finds use in all such web systems, processes and/or apparatus.

Turning now to FIG. 1, horizontal and vertical frame plates 14 and 15 support the various system components. The drive mechanism 16 is illustrated in an exploded position adjacent the vertical frame plate on which it is carried. Thev drive mechanism includes the electric motor 17 drivingly coupled to thetake-up reel v and the drag brake-or clutch 18 coupled to supply reel 4. The motor coupled to'the take-up reel pulls the web.3 from the supply reel against thebias force provided by the drag brake to maintain tension in the web whether it is moving or at rest. The web isthr eaded under the first idle roller 19 and over the image roller 20. From the image roller, the web is threaded: around the thermo roller 1 and wrap adjust device 2;'over the exit idle roller 21; across the display idle rollers 22 and 23 and viewing screen 24; and onto the take-up reel 5.

As mentioned earlier, the web is charged as it passes corotron 9, exposed as it traversed means and developed as it passes the thermo roller 1. r t

The corotron includes a thin conductive wire coupled to a high electrical potential source. The web substrate is conductiveand is coupled to a suitable potential, e.g. ground, through the image roller 20. The image roller is a conductive'roller electrically coupled to ground, for example, to ground the web. The potential difference between the web substrate and corotron wire yields a flow of ions and other charged particles tioned in its path. The light beam may be that generated at the face of a cathode ray tube. Alternately, the

The thermo-roller includes a relatively large diameter roller having an appropriate heating (or cooling in another system) element within its volume. Examples of suitable thermo energy elements include: an electrical resistance heater; and infra-red lamp; hot or cold liquid coils; and hot or cold vapor coils. The object is to exchange thermo energy between the web and the periphery of the thermo roller. Most conveniently, the thermo roller periphery is heated or cooled by conduction through the walls of the roller. How the walls are heated is not particularly important since this may be a matter of design convenience. For example, radiation and/or convection may be the principal means for heating the inside walls of the roller. However, this invention is not limited to the methods of heating or cooling since the invention may be practiced even when the thermo-roller is a hollow glass cylinder having an infrared lamp within its volume. The primary requirement for this invention is to provide a web location at which a a highly efficient heat transfer occurs. This location is the periphery of the thermo-roller and the wrap adjust device cooperates to control web temperature by varying the contact area between the web and thermo rollet.

The wrap adjust device includes two pivot arms journaledat opposite ends of they thermo roller about its axis. Member 40 is one of the pivot arms and is typical of the other positioned at the hidden (as viewed in FIG. 1) end of the thermo-roller. A wrap adjust roller 41 is journaled near the free ends of the pivot arms by suitable bearings, bearing 42 being typical. A look nut 43 is coupled to the axle'of the thermo roller and abutts against pivot arm 40 to hold it against rotation. When the lock nut is loosened, the pivot arms are rotated to vary the location of the wrap adjust roller relative to the thermo roller. With this scheme, the wrap roller can be positioned at an infinite number of locations on a circular path around the thermo roller. The clearance between the peripheries of the wrap adjust and thermo rollers is selected to be sufficiently great to prevent contact between the web and thermo roller at least at one position of the wrap roller. The function of web separation is discussed in more detail below.

The lock nut 43 is representative of one of many mechanisms for controlling the position of the wrap adjust roller relative to the periphery of the thermo roller.

In more sophisticated systems, the lock nut is replaced by a stepping motor or other position control device. The position control device is operated automatically in response to the movement of the web. An example, is an electrical motor coupled to the pivot arms that is energized to rotate in a first direction a fixed number of angular degrees when the motor 17 coupled to the take-up reel 5 is started and a fixed number of angular degrees in the opposite direction when motor 17 is stopped. Switching apparatus capable of such opera tion is well known. The described apparatus causes the web to be pulled into contact with the periphery of the thermo roller when the web moves and to be pulled out-of-contact with the thermo roller when the web stops.

FIGS. 2-4 depict the operation of the wrap adjust device except the pivot arms are deleted for clarity of presentation. The angle theta is the angle by which the web 3. is diverted when around the thermo roller whileout of contactwith the wrap adjustroller 41. The

angle theta also defines themaxirnum contact areabetween the thermo roller and web. The larger the angle theta, the greater the amount of heat exchange occurs between the web and thermo roller because of the greater period of time in which heat is exchanged.

. The angle theta also defines the minimum dimension forthe pivotradius 5.0 which is the distances between the axes .of rotation of the wrap adjust and thermo rollers. When the radius 50 is sufficient to position the wrap adjust roller near the apex of angle 50, a minimum contact occurs between the web and thermo rol- V ler. Making the radiusSO even larger to position the wrap roller to the right of the apex of angle theta, as'in FIG. 4, results in complete separation between the web or the apex position shown in FIG. 4.

If the thermo roller is heated (versus cooled), the temperature of theweb is'raised when roller 41 is at the home position. The web temperatureis lowered-by the ambient air when the wrap roller is located at the apex I position. The surface contact can be varied between the two extremes by locating the wrap roller at intermediate positionssuch as illustrated in FIGS.

The angle theta is selected for the needs of a particular systemand may be varied from zero degrees to 180 degrees. In the event that theta is zero degrees, the web is wrapped half way around the thermo roller and the radius of the wrap roller must be greater than the radius of the thermorollerto obtain "complete separation between the web and thermo roller. The apex position in this case is'at infinity. When theta is 180 degrees, the contact between the web is substantially a line at the tangent point betweenthe web and thermo roller. The

wrap roller separates the two when positioned at the apex of angle theta, in this case the tangent point. Al-

ternately, the wrap roller is positioned on the otherside of the web. In this case, there is minimum surface contact when the wrap roller is at the apex or tangent point and the contact area is increased when the roller is moved to another position. Since the web is between the wrap and thermo roller, the wrap roller pulls the web into greater contact with the thermo roller when moved from the apex position.

Other variations and embodiments of this invention will be apparent to those skilled in theart from the presentdescription and drawings.

What is claimed is: Y

' 1'. A method of controlling the temperature of a heatsensitive web comprising therrno"roller.'

2;. Themethod. of claim 1 wherein said web is positioned between the thermo r'ollerl and wrap adjust roller means. r t

3. The method of claim 1 wherein said wrap adjust roller means is positioned between the web and thermo roller. 7 r

4. The method of claim 1 wherein the radius of said circular path is sufficientto place saidwrap adjust roller means near the apex of the angle theta.

5. The method of claim 4 wherein said radius is sufficient to effect complete separation of the web from the thermo roller.

6. The method of claim 1 wherein said thermo energy source includes means for heating the thermo roller.

7. The method of claim 1 wherein said thermo energy source includes means for cooling the thermo roller.

8. The method of claim 1 wherein said web includes cles and softenable material.

* 9. The method of claim 1 wherein saidjweb' includes a thermoplastic deformation member including a thermoplastic insulating layer and a photoconductive layer.

10. Apparatus for varying the contact area between a web and a thermo roller comprising:

a. a thermo roller positioned to have a around a portion of its periphery; b. a thermo energy source coupled to said thermo roller; I

c. wrap adjust roller means supported for movement along a coincident, concentric circular path'around the periphery of said thermo roller forvarying-the surface area contact between the web and said thermo roller.

11. Apparatus according to claim 10 further including position control means coupled to said wrap adjust roller means for moving the wrap adjustment roller means between various positions along said circular path to correspondingly-vary the surface area contact between the web and said thermo roller.

12. Apparatus according to claim 11 wherein said position control device includes switching means for moving said wrap adjust roller means to a position for completely separating the web from said thermo roller.

13. Apparatus according to claim 10 wherein said wrap adjust roller means is journeled in at least one pivot arm rotatably supported about the rotation axis of said thermo roller.

14. Apparatus, according to claim 11 wherein said thermo energy source includes means for heating said webwrapped thermo roller.

15. Apparatus'according to claim 11 wherein said thermo energy source includes means for cooling said thermo roller. a

16. Apparatus according to claim ,11 wherein said thermo roller and said wrap adjust roller are on opposite sides of the web.

. 17. The method of claim 1 wherein said wrap adjust roller means is a single roller.

18. The apparatus of claim .10 wherein said wrap adjust roller means is a single roller.

a migration imaging member comprising image parti- 

1. A method of controlling the temperature of a heat sensitive web comprising wrapping said web about a thermo roller having a thermo energy source coupled to it to divert the direction of the web by an angle theta, supporting wrap adjust roller means for movement along at least a portion of a coincident, concentric circular path around the periphery of the thermo roller and moving said wrap adjust roller means between at least two positions on said circular path for varying the surface area contact between the web and thermo roller.
 2. The method of claim 1 wherein said web is positioned between the thermo roller and wrap adjust roller means.
 3. The method of claim 1 wherein said wrap adjust roller means is positioned between the web and thermo roller.
 4. The method of claim 1 wherein the radius of said circular path is sufficient to place said wrap adjust roller means near the apex of the angle theta.
 5. The method of claim 4 wherein said radius is sufficient to effect complete separation of the web from the thermo roller.
 6. The method of claim 1 wherein said thermo energy source includes means for heating the thermo roller.
 7. The method of claim 1 wherein said thermo energy source includes means for cooling the thermo roller.
 8. The method of claim 1 wherein said web includes a migration imaging member comprising image particles and softenable material.
 9. The method of claim 1 wherein said web includes a thermoplastic deformation member including a thermoplastic insulating layer and a photoconductive layer.
 10. Apparatus for varying the contact area between a web and a thermo roller comprising: a. a thermo roller positioned to have a web wrapped around a portion of its periphery; b. a thermo energy source coupled to said thermo roller; c. wrap adjust roller means supported for movement along a coincident, concentric circular path around the periphery of said thermo roller for varying the surface area contact between the web and said thermo roller.
 11. Apparatus according to claim 10 further including position control means coupled to said wrap adjust roller means for moving the wrap adjustment roller means between various positions along said circular path to correspondingly vary the surface area contact between the web and said thermo roller.
 12. Apparatus according to claim 11 wherein said position control device includes switching means for moving said wrap adjust roller means to a position for completely separating the web from said thermo roller.
 13. Apparatus according to claim 10 wherein said wrap adjust roller means is journeled in at least one pivot arm rotatably supported about the rotation axis of said thermo roller.
 14. Apparatus according to claim 11 wherein said thermo energy source includes means for heating said theRmo roller.
 15. Apparatus according to claim 11 wherein said thermo energy source includes means for cooling said thermo roller.
 16. Apparatus according to claim 11 wherein said thermo roller and said wrap adjust roller are on opposite sides of the web.
 17. The method of claim 1 wherein said wrap adjust roller means is a single roller.
 18. The apparatus of claim 10 wherein said wrap adjust roller means is a single roller. 